The present invention relates to additives to hot melt adhesives based upon copolyamides which improve the adhesive strength and wash-fastness of the latter.
Hot melt adhesives are used for the coating of textile insert materials for face setting, especially in the so-called spot-wise coating method. Thermoplastic synthetic resins are used as the hot melt adhesives. Thus, it is known to use high pressure polyethylene for textiles which are exposed to only minor stresses. More advantageous bonds are obtained with the use of so-called low pressure polyethylene. The last-mentioned compounds have a very good wash-fastness, but show no or only very little resistance against cleaning agents employed in dry cleaning. Copolymers, especially tertiary and also higher copolyamides, have also been employed for a long time. Hot melt adhesives based upon copolyamides are basically of satisfactory resistance to dry cleaning agents. The wash-fastness, which can be denoted as good to satisfactory, depending on the composition, needs to be improved, however. In general, copolyamide hot melt adhesives of a higher melting point are more wash-fast and this brings the disadvantage of higher processing temperatures and/or the necessity of employing higher pressures and thus longer cycle times during processing.
The state of the art of polyamides may be ascertained by reference to Kirk-Othmer "Encyclopedia of Chemical Technology," Vol. 16 (1968), pp 1 - 105, particularly pp. 22 and 23 which disclose copolymerization, pp. 92-95 which disclose additives, and p. 101 which discloses soluble polyamides made by copolymerization, the disclosures of which are incorporated herein. The preparation of copolyamides useful in the present invention may be ascertained by reference to U.S. Pat. No. 3,410,832; British Pat. No. 1,168,404; German Published Pat. application No. 2,030,741, and Japanese Pat. No. 68-22,875.
The acid amides of the general formula useful in the present invention are available as commercial compositions; their preparationn is known in the art and may be effected as disclosed further in the specification.
The aminoalkyl phenols of the general formula useful in the present application are also available as commercial compositions, and their preparation is known in the art and may be effected as disclosed further in the specification.
Hot melt adhesives which are used in the form of powders or so-called pastes are known as disclosed in US-Pat. Nos. 3,515,702; 3,839,121 and are prepared as disclosed in German Published Pat. applications Nos. 2,007,971; 2,229,308; and 2,307,346. Also, a great variety of additives are known, which serve in part for reducing the melting points of the copolyamides, for example plasticizers and/or additives of homopolyamides as disclosed in French Pat. No. 1,367,481; U.S. Pat. No. 3,306,865; and German Published Pat. applications Nos. 1,794,247; 1,930,129; 2,237,674; and 1,794,106. The conventional additives, however, are not as yet fully satisfactory.